Guys i have an AWD V8.. last night on way home my truck went to 4lo on its own while i pulled my trailer with my 4 wheelers doin 65. As u can imagine the outcome doesnt't look good. There's alot of grinding coming from what i believe to be my trans. case.. any advice and experience really appreciated. But my truck seems to be locked up.. like if brakes were applied at moments . Trans and engine seem fine other than grinding sound from what i think is coming from trans. case.. thnx in advance for any and all help..

good be tcase, could be a diff, could be the tranny. Honestly, I'd say take the t-case off, pop her open, and check for metal shavings.

Well guys removed my actuator to look it over then drained oil on t case.. results i think will speak for themselves..


Now was wondering if anyone can give me some advice on options to either replace, rebuild, and costs not a whole lot of replies so im guessing not very common but any help with info is very appreciated guys... Thanks.

I say to hell with it. Seriously. Since the TCASE is electronically controlled, it means that something odd/funky had to occur with the electronics to cause a sudden shift.

either that or the entire system is buggered and that caused a bump or similar other "who knows" occurrence to cause random 4lo transfer at highway speeds.

It isn't supposed to be possible. You have several safe stop mechanisms to prevent intentional or accidental slip into 4lo at highway speeds, meaning that they all failed. At this point, I would consider entire system suspect, electronics on up.

So, you need to decide. I don't think it is worth it to try to bring 4lo back. Unless you used it often, say more than 1 a year, it isn't worth the pain. 4hi gets you 98% of total usage for practically every situation.

Focus on that. Does 4hi work or is the entire system destroyed? Can you force it into 4hi and then be done with it? If so, do that. Did it do any damage to anything else?

How many miles on the 4runner?

For me I like a completely working system not just have 4High, I want 4low to work too.

Put everything back together and see if it goes into 4WD Low. Make sure the connectors to the actuator are clean.

At this point it is premature to say you need a rebuilt Tcase with the shavings you found. Is it possible? Yes, but first find out the cause of the hiccup. You do not want to get the Tcase rebuilt to have 4Lo come on again unintentionally running your Tcase again. If everything works without any grinding noise than everything should be fine. Seems like an electronic issue that caused this not mechanical.

The Toyota service manual has a very good diagram with a table in there to check all possible electrical problems with the actuator with a digital volt meter. Download that and start from there.

I disagree. It is a cost benefit analysis. Why waste money on the lo system if you never use it?

Getting the 4lo system to work doubles the requirements necessary to make it happen. You need a 2 set transfer case, you need a functioning actuator to make the change. A 100% functioning 4hi system needs none of that.

If you can get it into 4hi, leave it. Be done with it. If you need low gearing, shove it into 1st gear. Sometimes it is better to look at need vs. want.

Also, it isn't just electronic. The electronic system doesn't shear metal. The departure from norm may have been electronic, but the damage is now more than electronic. Grinding and largish metal bits are not "electronic" that qualifies as metal.

Those are not the minuscule shavings you expect to see over 100, 200k.... those are what you see when stuff breaks.


If the truck is grinding and not moving, then that means that the tcase gearing is probably busted. It would be worth it to have a qualified tech take a look. If I were in your shoes? Ask them 1. damage 2. if you can get it back into normal 4hi and then rip disable to 4lo transfer to prevent this from happening again.

Guys very good points. DC only thing is doesnt it need to be fully functional since it is a full time AWD system? And i don't use 4low often if any at all.. truck has 185k and used mostly for trails and light towing.. If anything for the truck to go into 4lo on its own makes me second guess Toyotas design on this. Thats a serious safety issue imho.. Fortunately no traffic behind me when it occured.. very unnerving ferling when it did.. thanks alot for tesponses guys im pretty down on this right now as i do lovd this truck. Now im wondering if i should sell or keep it from fear of this happening again which validates DCs points..

This is my point. Your truck is a FULL TIME 4wd. It can be in either 4hi or 4lo.

Run it in 4hi. Won't matter one bit. I have the same vehicle and am very familiar with it. You need the center diff and the 4hi system engaged, yes; but you don't need the 4lo actuator to do this.

Thanks guys. I guess now i gotta look around for a used one or see how much to get it rebuilt..

get a tcase with lower milage used for like 300 bucks, or a whole new to you tranny for like 700.

28.,

Sorry this happened to you.

What were the symptoms?

5th gear is supposed to be unavailable in low range so at 65mph I'd think all the wheels should have locked up - or the engine should have blown or something if it somehow managed to get into low range which I'm not sure is even possible from a mechanical point of view.

What happened exactly? Did it the engine start revving real high combined with some serious engine braking? How'd you get home?

You said you removed the Actuator? How did you do that without removing the transfercase? (By the way, its not a trick question... The actuator is pinned internally to the transfercase so you shouldn't have been able to remove it at all)

I was going up a slight incline actually so i wanna say i was in fourth gear. The truck just hunkered down, revs did come up and it could have been slower than 65 but it was at least 50 for sure cause i was already on highway.. i already drained the oil on my t case and oil had alot of metal pieces in it.. truck actually does move, engine sounds fine,no smoking, and tranny shifts fine.. grinding noise was coming from t case area that's what made me check it first.. As far as removing actuator i unbolted it and simply wiggled it off. Wasn't really that difficult. Should it have been? :-\

In this picture the shaft seems like its part of the transfer case and not the actuator. So when you remove the actuator from the T-case is only the shaft visible like in this picture? If so than you can remove the actuator and that shaft stays in the actuator since its pinned inside like you mentioned.

So many conflicting things I read about the actuator, just trying to understand things. It would be nice if someone did a proper DIY on this! surprised this has not been done yet since the 4runner has been out since 2003, 11 years now.

Here is the pic.



And the thread.

4lo Actuator Rebuild